LONDON—The U.K. said it will move ahead with plans to introduce a first-of-its-kind tax on locally generated revenue by large technology firms—the most concrete attempt yet by an industrialized nation to rewrite the world’s tax code for the digital era.

The new tax comes as dozens of other countries are contemplating similar levies on digital services sold by companies such as Alphabet Inc.’s Google and Facebook Inc. These governments are hoping to capture more revenue from such services as economic activity increasingly shifts...